PIC

NAME

pic - compile pictures for troff or TeX

SYNOPSIS

pic
[
-nvCSU
]
[
filename
...
]
pic-t
[
-cvzCSU
]
[
filename
...
]

DESCRIPTION

This manual page describes the GNU version of
pic,
which is part of the groff document formatting system.
pic
compiles descriptions of pictures embedded within
troff
or TeX input files into commands that are understood by TeX or
troff.
Each picture starts with a line beginning with
.PS
and ends with a line beginning with
.PE.
Anything outside of
.PS
and
.PE
is passed through without change.

It is the user[aq]s responsibility to provide appropriate definitions
of the
PS
and
PE
macros.
When the macro package being used does not supply such definitions
(for example, old versions of -ms), appropriate definitions can be
obtained with
-mpic:
These will center each picture.

OPTIONS

Options that do not take arguments may be grouped behind a single
-.
The special option
--
can be used to mark the end of the options.
A filename of
-
refers to the standard input.

-C

Recognize
.PS
and
.PE
even when followed by a character other than space or newline.

-S

Safer mode; do not execute
sh
commands.
This can be useful when operating on untrustworthy input (enabled by
default).

-U

Unsafe mode; revert the default option
-S.

-n

Don[aq]t use the groff extensions to the troff drawing commands.
You should use this if you are using a postprocessor that doesn[aq]t
support these extensions.
The extensions are described in
groff_out(5).
The
-n
option also causes
pic
not to use zero-length lines to draw dots in troff mode.

-t

TeX mode.

-c

Be more compatible with
tpic.
Implies
-t.
Lines beginning with
\
are not passed through transparently.
Lines beginning with
.
are passed through with the initial
.
changed to
\.
A line beginning with
.ps
is given special treatment:
it takes an optional integer argument specifying
the line thickness (pen size) in milliinches;
a missing argument restores the previous line thickness;
the default line thickness is 8 milliinches.
The line thickness thus specified takes effect only when a
non-negative line thickness has not been specified by use of the
thickness
attribute or by setting the
linethick
variable.

-v

Print the version number.

-z

In TeX mode draw dots using zero-length lines.

The following options supported by other versions of
pic
are ignored:

-D

Draw all lines using the \D escape sequence.
pic
always does this.

-T dev

Generate output for the
troff
device
dev.
This is unnecessary because the
troff
output generated by
pic
is device-independent.

USAGE

This section describes only the differences between GNU
pic
and the original version of
pic.
Many of these differences also apply to newer versions of Unix
pic.
A complete documentation is available in the file

/usr/share/doc/groff-1.22.3/pic.ms

TeX mode

TeX mode is enabled by the
-t
option.
In TeX mode,
pic
will define a vbox called
\graph
for each picture.
Use the
figname
command to change the name of the vbox.
You must yourself print that vbox using, for example, the command

\centerline{\box\graph}

Actually, since the vbox has a height of zero (it is defined with
\vtop) this will produce slightly more vertical space above the
picture than below it;

\centerline{\raise 1em\box\graph}

would avoid this.

To make the vbox having a positive height and a depth of zero
(as used e.g. by lx][aq]s
graphics.sty),
define the following macro in your document:

\def\gpicbox#1{% \vbox{\unvbox\csname #1\endcsname\kern 0pt}}

Now you can simply say
\gpicbox{graph}
instead of \box\graph.

You must use a TeX driver that supports the
tpic
specials, version 2.

Lines beginning with
\
are passed through transparently; a
%
is added to the end of the line to avoid unwanted spaces.
You can safely use this feature to change fonts or to
change the value of
\baselineskip.
Anything else may well produce undesirable results; use at your own risk.
Lines beginning with a period are not given any special treatment.

Commands

forvariable=expr1toexpr2 [by [*],expr3/] doXbodyX

Set
variable
to
expr1.
While the value of
variable
is less than or equal to
expr2,
do
body
and increment
variable
by
expr3;
if
by
is not given, increment
variable
by 1.
If
expr3
is prefixed by
*
then
variable
will instead be multiplied by
expr3.
The value of
expr3
can be negative for the additive case;
variable
is then tested whether it is greater than or equal to
expr2.
For the multiplicative case,
expr3
must be greater than zero.
If the constraints aren[aq]t met, the loop isn[aq]t executed.
X
can be any character not occurring in
body.

ifexprthenXif-trueX [elseYif-falseY]

Evaluate
expr;
if it is non-zero then do
if-true,
otherwise do
if-false.
X
can be any character not occurring in
if-true.
Y
can be any character not occurring in
if-false.

printarg...

Concatenate the arguments and print as a line on stderr.
Each
arg
must be an expression, a position, or text.
This is useful for debugging.

commandarg...

Concatenate the arguments
and pass them through as a line to troff or TeX.
Each
arg
must be an expression, a position, or text.
This has a similar effect to a line beginning with
.
or
\,
but allows the values of variables to be passed through.
For example,

.PS
x = 14
command ".ds string x is " x "."
.PE
\*[string]

prints

x is 14.

shXcommandX

Pass
command
to a shell.
X
can be any character not occurring in
command.

copy",filename/"

Include
filename
at this point in the file.

copy [",filename/"] thruXbodyX [until",word"]

copy [",filename/"] thrumacro [until",word"]

This construct does
body
once for each line of
filename;
the line is split into blank-delimited words,
and occurrences of
$i
in
body,
for
i
between 1 and 9,
are replaced by the
i-th
word of the line.
If
filename
is not given, lines are taken from the current input up to
.PE.
If an
until
clause is specified,
lines will be read only until a line the first word of which is
word;
that line will then be discarded.
X
can be any character not occurring in
body.
For example,

The commands to be performed for each line can also be taken
from a macro defined earlier by giving the name of the macro
as the argument to
thru.

reset

reset variable1/[,] variable2 ...

Reset pre-defined variables
variable1

,
variable2
... to their default values.
If no arguments are given, reset all pre-defined variables to their
default values.
Note that assigning a value to
scale
also causes all pre-defined variables that control dimensions to be
reset to their default values times the new value of scale.

plotexpr [",text"]

This is a text object which is constructed by using
text
as a format string for sprintf
with an argument of
expr.
If
text
is omitted a format string of
s%gs
is used.
Attributes can be specified in the same way as for a normal text
object.
Be very careful that you specify an appropriate format string;
pic
does only very limited checking of the string.
This is deprecated in favour of
sprintf.

variable := expr

This is similar to
=
except
variable
must already be defined,
and
expr
will be assigned to
variable
without creating a variable local to the current block.
(By contrast,
=
defines the variable in the current block if it is not already defined
there, and then changes the value in the current block only.)
For example, the following:

.PS
x = 3
y = 3
[
x := 5
y = 5
]
print x " " y
.PE

prints

5 3

Arguments of the form

X anything X

are also allowed to be of the form

{ anything }

In this case
anything
can contain balanced occurrences of
{
and
}.
Strings may contain
X
or imbalanced occurrences of
{
and
}.

String comparison expressions must be parenthesised in some contexts
to avoid ambiguity.

Other Changes

A bare expression,
expr,
is acceptable as an attribute;
it is equivalent to
dir expr,
where
dir
is the current direction.
For example

line 2i

means draw a line 2 inches long in the current direction.
The [oq]i[cq] (or [oq]I[cq]) character is ignored; to use another
measurement unit, set the
scale
variable to an appropriate value.

The maximum width and height of the picture are taken from the variables
maxpswid
and
maxpsht.
Initially these have values 8.5 and 11.

Scientific notation is allowed for numbers.
For example

x = 5e-2

Text attributes can be compounded.
For example,

"foo" above ljust

is valid.

There is no limit to the depth to which blocks can be examined.
For example,

[A: [B: [C: box ]]] with .A.B.C.sw at 1,2circle at last [].A.B.C

is acceptable.

Arcs now have compass points determined by the circle of which the arc
is a part.

Circles, ellipses, and arcs can be dotted or dashed.
In TeX mode splines can be dotted or dashed also.

Boxes can have rounded corners.
The
rad
attribute specifies the radius of the quarter-circles at each corner.
If no
rad
or
diam
attribute is given, a radius of
boxrad
is used.
Initially,
boxrad
has a value of 0.
A box with rounded corners can be dotted or dashed.

Boxes can have slanted sides.
This effectively changes the shape of a box from a rectangle to an
arbitrary parallelogram.
The
xslanted
and
yslanted
attributes specify the x and y~offset of the box[aq]s upper right
corner from its default position.

The
.PS
line can have a second argument specifying a maximum height for
the picture.
If the width of zero is specified the width will be ignored in computing
the scaling factor for the picture.
Note that GNU
pic
will always scale a picture by the same amount vertically as well as
horizontally.
This is different from the
DWB
2.0
pic
which may scale a picture by a different amount vertically than
horizontally if a height is specified.

Each text object has an invisible box associated with it.
The compass points of a text object are determined by this box.
The implicit motion associated with the object is also determined
by this box.
The dimensions of this box are taken from the width and height attributes;
if the width attribute is not supplied then the width will be taken to be
textwid;
if the height attribute is not supplied then the height will be taken to be
the number of text strings associated with the object
times
textht.
Initially
textwid
and
textht
have a value of 0.

In (almost all) places where a quoted text string can be used,
an expression of the form

sprintf(sformats, arg,...)

can also be used;
this will produce the arguments formatted according to
format,
which should be a string as described in
printf(3)
appropriate for the number of arguments supplied.

The thickness of the lines used to draw objects is controlled by the
linethick
variable.
This gives the thickness of lines in points.
A negative value means use the default thickness:
in TeX output mode, this means use a thickness of 8 milliinches;
in TeX output mode with the
-c
option, this means use the line thickness specified by
.ps
lines;
in troff output mode, this means use a thickness proportional
to the pointsize.
A zero value means draw the thinnest possible line supported by
the output device.
Initially it has a value of -1.
There is also a
thick[ness]
attribute.
For example,

circle thickness 1.5

would draw a circle using a line with a thickness of 1.5 points.
The thickness of lines is not affected by the
value of the
scale
variable, nor by the width or height given in the
.PS
line.

Boxes (including boxes with rounded corners or slanted sides),
circles and ellipses can be filled by giving them an attribute of
fill[ed].
This takes an optional argument of an expression with a value between
0 and 1; 0 will fill it with white, 1 with black, values in between
with a proportionally gray shade.
A value greater than 1 can also be used:
this means fill with the
shade of gray that is currently being used for text and lines.
Normally this will be black, but output devices may provide
a mechanism for changing this.
Without an argument, then the value of the variable
fillval
will be used.
Initially this has a value of 0.5.
The invisible attribute does not affect the filling of objects.
Any text associated with a filled object will be added after the
object has been filled, so that the text will not be obscured
by the filling.

Three additional modifiers are available to specify colored objects:
outline[d]
sets the color of the outline,
shaded
the fill color, and
colo[u]r[ed]
sets both.
All three keywords expect a suffix specifying the color, for example

circle shaded green outline black

Currently, color support isn[aq]t available in TeX mode.
Predefined color names for
groff
are in the device macro files, for example
ps.tmac;
additional colors can be defined with the
.defcolor
request (see the manual page of
troff(1)
for more details).

To change the name of the vbox in TeX mode, set the pseudo-variable
figname
(which is actually a specially parsed command) within a picture.
Example:

.PSfigname = foobar;....PE

The picture is then available in the box
\foobar.

pic
assumes that at the beginning of a picture both glyph and fill color are
set to the default value.

Arrow heads will be drawn as solid triangles if the variable
arrowhead
is non-zero and either TeX mode is enabled or the
-n
option has not been given.
Initially
arrowhead
has a value of 1.
Note that solid arrow heads are always filled with the current outline
color.

The troff output of
pic
is device-independent.
The
-T
option is therefore redundant.
All numbers are taken to be in inches; numbers are never interpreted
to be in troff machine units.

Objects can have an
aligned
attribute.
This will only work if the postprocessor is
grops,
or
gropdf.
Any text associated with an object having the
aligned
attribute will be rotated about the center of the object
so that it is aligned in the direction from the start point
to the end point of the object.
Note that this attribute will have no effect for objects whose start
and end points are coincident.

In places where
nth
is allowed
[oq]expr[cq]th
is also allowed.
Note that
[cq]th
is a single token: no space is allowed between the
[cq]
and the
th.
For example,

for i = 1 to 4 do {
line from [oq]i[cq]th box.nw to [oq]i+1[cq]th box.se
}

CONVERSION

To obtain a stand-alone picture from a
pic
file, enclose your
pic
code with
.PS
and
.PE
requests;
roff
configuration commands may be added at the beginning of the file, but no
roff
text.

It is necessary to feed this file into
groff
without adding any page information, so you must check which
.PS
and
.PE
requests are actually called.
For example, the mm macro package adds a page number, which is very
annoying.
At the moment, calling standard
groff
without any macro package works.
Alternatively, you can define your own requests, e.g. to do nothing:

.de PS
..
.de PE
..

groff
itself does not provide direct conversion into other graphics file
formats.
But there are lots of possibilities if you first transform your
picture into PostScript® format using the
groff
option
-Tps.
Since this
ps-file
lacks BoundingBox information it is not very useful by itself, but it
may be fed into other conversion programs, usually named
ps2other
or
pstoother
or the like.
Moreover, the PostScript interpreter
ghostscript
(gs)
has built-in graphics conversion devices that are called with the option

gs -sDEVICE=<devname>

Call

gs --help

for a list of the available devices.

An alternative may be to use the
-Tpdf
option to convert your picture directly into
PDF
format.
The MediaBox of the file produced can be controlled by passing a
-P-p
papersize to groff.

As the Encapsulated PostScript File Format
EPS
is getting more and more important, and the conversion wasn[aq]t
regarded trivial in the past you might be interested to know that
there is a conversion tool named
ps2eps
which does the right job.
It is much better than the tool
ps2epsi
packaged with
gs.

For bitmapped graphic formats, you should use
pstopnm;
the resulting (intermediate)
PNM
file can be then converted to virtually any graphics format using the
tools of the
netpbm
package .

FILES

u+3n

/usr/share/groff/1.22.3/tmac/pic.tmac
Example definitions of the
PS
and
PE
macros.

BUGS

Input characters that are invalid for
groff
(i.e., those with
ASCII
code 0, or 013 octal, or between 015 and 037 octal, or between 0200 and 0237
octal) are rejected even in TeX mode.

The interpretation of
fillval
is incompatible with the pic in 10th edition Unix,
which interprets 0 as black and 1 as white.

PostScript® is a registered trademark of Adobe Systems Incorporation.

COPYING

Copyright [co] 1989-2014 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that this permission notice may be included in
translations approved by the Free Software Foundation instead of in
the original English.